Timing of nautical twilight where you are Twilight Around the PolesĪt high latitudes and around the summer solstice, the Sun does not move lower than 18 degrees below the horizon, so twilight can last from sunset to sunrise. In Oslo (about 60 degrees North) and the northernmost tip of Antarctica (about 60 degrees South), the same process takes roughly 1 hour and 35 minutes.In New York (about 40 degrees North) and Wellington (about 40 degrees South), during the equinoxes, it takes about 1 hour from the beginning of nautical twilight until the Sun rises.For instance, in Quito, Ecuador, which is very close to the Equator, nautical twilight begins only about 45 minutes before sunrise during the equinoxes.Īt higher latitudes, in both the Northern and Southern Hemisphere, the Sun's path makes a lower angle with the horizon, so the twilight phases last longer: In locations where the Sun is directly overhead at noon-for example at the equator during the equinoxes-the Sun traverses the horizon at an angle of 90 degrees, making for swift transitions between night and day with relatively short twilight phases. The duration of each twilight phase depends on the latitude and the time of the year. It marks the beginning of astronomical twilight.Īstronomical terms & definitions Timing and Length Similarly, nautical dusk is the instant when the geometric center of the Sun is 12 degrees below the horizon in the evening. Nautical dawn is the moment when the geometric center of the Sun is 12 degrees below the horizon in the morning. However, unlike the term twilight, which describes a time span, the terms dawn and dusk refer to exact moments during the transitions between day and night. This is why it is called nautical twilight.įind the planets in the night sky Nautical Dawn and Nautical Duskĭifferent degrees of twilight in the twilight phases in the morning are also colloquially called dawn, while the twilight phases in the evening are referred to as dusk. Many of the brighter stars can also be seen, making it possible to use the position of the stars in relation to the horizon to navigate at sea. In clear weather conditions, the horizon is faintly visible during this twilight phase. During nautical twilight, the geometric center of the Sun's disk is between 6 and 12 degrees below the horizon. The 3 twilight phases on a world map Nautical TwilightĮach twilight phase is defined by the solar elevation angle, which is the position of the Sun in relation to the horizon. Astronomers differentiate between 3 phases: Twilight is the time between day and night when the Sun is below the horizon but its rays still light up the sky. The moments when 99% of people see sunlight During nautical twilight, both the horizon and the brighter stars are usually visible.
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